Environmental stress and developmental stability in dentition of the yellowstone grizzly bears

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

Asymmetry in bilateral traits is often used to assess an individual's quality and stress resistance, but stress-induced variation in developmental stability is largely undocumented for free-living populations. Over many years, grizzly bears (Ursus arctos horribilis) extensively foraged around garbage dumps in Yellowstone National Park. Abrupt closure of these dumps 26 years ago was a severely stressful event and was followed by excessive mortality and a many-fold increase in grizzly home-range size. I examine how this stress affected developmental stability by comparing dentition of bears born before and after the dump closure. I predicted that (1) asymmetry in dentition should be greater in bears born after dump closure compared to before closure, and asymmetry in sexually selected canines should change more than nonsexually selected premolars following dump closure and (2) the relationship between tooth asymmetry and tooth size should change in the populations following the stressful events as compared with populations before stressful events. I found that developmental stability of canines, which are under directional sexual selection in males, was more responsive to stress compared to that of male premolars or female dentition (both under stabilizing selection), and, because of the increased cost of canine production, fewer animals were able to achieve both large size and symmetrical development of these teeth, and thus the slope of the relationship between fluctuating asymmetry and canine size increased. I conclude that stress appears to act as an honesty-reinforcement mechanism in sexual selection for symmetrical dentition.

Original languageEnglish (US)
Pages (from-to)339-344
Number of pages6
JournalBehavioral Ecology
Volume9
Issue number4
DOIs
StatePublished - Jan 1 1998
Externally publishedYes

Keywords

  • Dentition
  • Developmental stability
  • Environmental stress
  • Grizzly bears
  • Sexual selection
  • Ursus arctos horribilis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology

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